1. Technical Field
The present invention relates to a transmission-type display device, a head-mounted display device, a display system and a control method for a display device for making the user visually recognize a display image screen as a virtual image.
2. Related Art
According to the related art, as a display device of this type, an optical transmission-type head-mounted display device mounted on the user's head is known (see JP-A-2012-163637). This display device is configured in such a way that the user can visually recognizes an image as a virtual image and can also directly visually recognize the exterior (real scenery).
Meanwhile, the display device of this type uses a light guide panel having a half mirror portion to make the user visually recognize a virtual image. That is, the display device is configured to reflect and guide image light to the user's eyes by the half mirror portion, thereby making the user visually recognize a display image screen as a virtual image in the user's field of vision.
However, the related-art configuration can lead to eye fatigue and sick feeling due to the user's shifting his/her line of sight out of the display image screen (half mirror portion). That is, as the user shifts his/her line of sight out of the display image screen, the line of sight shifts to a part where there is no half mirror portion of the light guide panel and therefore the user sees the exterior through that part. Consequently, the field of vision can be distorted, causing the user to feel uncomfortable and leading to eye fatigue and sick feeling. Moreover, it is also conceivable that the line of sight may shift out of the light guide panel. In such a case, moving the line of sight into and out of the light guide panel can involve repeated focusing and therefore can lead to eye fatigue and sick feeling.